"…While we cannot say climate change "caused" Hurricane Harvey (that is an ill-posed question), we can say is that it exacerbated several characteristics of the storm in a way that greatly increased the risk of damage and loss of life. Climate change worsened the impact of Hurricane Harvey." -- Michael E. Mann, Director of the Earth System Science Center at Pennsylvania State University

It seems standard that weather changes day-to-day. Yet severe weather events like intense rain and snowstorms, flooding, extreme heat, drought, storms, hurricanes and tornadoes are becoming more frequent and extreme due to climate change. Superstorm Sandy and Hurricanes Katrina, Harvey and now Irma all have shown how severe weather can disrupt human health and safety, putting communities at risk.

Burning fossil fuels — such as coal, oil and gas — releases carbon dioxide into the atmosphere. Once released it traps heat, causing the Earth’s temperature to rise, which then changes wind, moisture and heat circulation patterns and leads to extreme weather events. Some relationships between extreme weather and health include:

Water contamination caused by bacteria, parasites and toxins can result when heavy precipitation overwhelms drainage or wastewater treatment systems.

Drowning in floodwaters poses a direct risk.

Injury can result from intense storms that knock down trees and power line and generate debris.

Mold can grow in flooded buildings, affecting indoor air quality and leading to increased asthma attacks and respiratory tract infections, such as pneumonia.

Loss, displacement, and job insecurity can increase stress and anxiety and worsen the mental health toll.

Standing water that remains after flooding creates a favorable environment for disease-carrying vectors including mosquitoes, increasing risk of vector-borne disease transmission including the Zika and West Nile viruses.

Drier soil and vegetationincrease the risk for larger and more intense wildfires, which can harm lung and heart health.

Drought-induced disruptions in food production can affect food security, and reduced access to healthy foods can contribute to malnutrition. Rising temperatures, variable climates and higher carbon dioxide levels in the air also decrease nutrients in crops.

Water shortages can have a severe impact on communities. People with livelihoods or cultural practices tied to the land — agricultural and indigenous communities, particularly — have a higher water shortage burden.

Stress and anxiety about land conditions can make existing mental health problems worse.

Children, older adults, people with chronic disease or mental health issues, those who work or exercise outdoors and live in low-income and minority communities need special attention. Neighborhoods with the fewest resources are most susceptible to extreme weather. Redlining practices (restricting access to housing and services based on race or ethnicity) have contributed to communities overpopulated with people of color in areas that are less desirable and more climate-vulnerable, such as flood zones and urban heat islands. Poor construction and low availability of affordable housing add to the unjust burden during and after a disaster.